HyperLogLog

Probabilistic counter for large or high cardinality datasets

Overview

HyperLogLog processor provides an implementation is an algorithm for the count-distinct problem, approximating the number of distinct elements in a multiset.

Calculating the exact cardinality of the distinct elements of a multiset requires an amount of memory proportional to the cardinality, which is impractical for very large data sets.

Example & DSL attributes

hyperloglog:
  name: distinctIMSICounter
  hash type: HASH64
  log2m: 3
  registry width: 3
  fields:
    - imsi

Response

The processor adds a distinctIMSICounter attribute with the following result

distinctIMSICounter:
  505010000011111 : 101
  904130454090869 : 78

Attributes schema

Attribute	Description	Data Type	Required
name	name of the counter	String
hash type	Hashing algorithm to be applied to event field. Supported types: DEFAULT (object hashcode), HASH32, HASH64	Long Default: DEFAULT
log2m	the number of probabilistic HLL registers	Integer Default: 11
registry width	The size (width) each register in bits. Supported range between 1 to 8 bits.	Integer Default: 5
fields	List of fields to perform distinct counts	List

Additional Information

• Article about HyperLogLog for more information